Remove ACCELERATED_OVERFLOW_SCROLLING as it is always off.

Source/core/rendering/RenderLayer.cpp

 /*
  * Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011, 2012 Apple Inc. All rights reserved.
  *
  * Portions are Copyright (C) 1998 Netscape Communications Corporation.
  *
  * Other contributors:
  *   Robert O'Callahan <roc+@cs.cmu.edu>
  *   David Baron <dbaron@fas.harvard.edu>
  *   Christian Biesinger <cbiesinger@web.de>
  *   Randall Jesup <rjesup@wgate.com>
@@ skipping 1947 matching lines @@
         return false;
     }
 
     ASSERT_NOT_REACHED();
     return m_needsCompositedScrolling;
 }
 
 void RenderLayer::updateNeedsCompositedScrolling()
 {
     updateCanBeStackingContainer();
-
-    bool needsCompositedScrolling = false;
     updateDescendantDependentFlags();
 
     ASSERT(renderer()->view()->frameView() && renderer()->view()->frameView()->containsScrollableArea(this));
-    bool forceUseCompositedScrolling = acceleratedCompositingForOverflowScrollEnabled()
+    bool needsCompositedScrolling = acceleratedCompositingForOverflowScrollEnabled()
         && canBeStackingContainer()
         && !hasUnclippedDescendant();
 
-#if ENABLE(ACCELERATED_OVERFLOW_SCROLLING)
-    needsCompositedScrolling = forceUseCompositedScrolling || renderer()->style()->useTouchOverflowScrolling();
-#else
-    needsCompositedScrolling = forceUseCompositedScrolling;
-#endif
     // We gather a boolean value for use with Google UMA histograms to
     // quantify the actual effects of a set of patches attempting to
     // relax composited scrolling requirements, thereby increasing the
     // number of composited overflow divs.
     if (acceleratedCompositingForOverflowScrollEnabled())
         HistogramSupport::histogramEnumeration("Renderer.NeedsCompositedScrolling", needsCompositedScrolling, 2);
 
     setNeedsCompositedScrolling(needsCompositedScrolling);
 }
 
@@ skipping 4421 matching lines @@
     }
 }
 
 void showLayerTree(const WebCore::RenderObject* renderer)
 {
     if (!renderer)
         return;
     showLayerTree(renderer->enclosingLayer());
 }
 #endif